Data Storage Devices (DSDs) are often used to record data onto or to reproduce data from storage media. DSDs can include different types of storage media, such as solid-state memory (e.g., flash memory) or a rotating magnetic disk. For such storage media, the DSD may use a logical to physical mapping that maps logical addresses for data to physical addresses indicating where the data is stored on the storage media.
In the case of solid-state memory, the DSD may use an indirection system to facilitate the rewriting of data associated with a particular logical address at different physical locations on the storage media. Such an indirection system may, for example, provide for wear leveling so that the solid-state memory is more evenly used to prolong a usable life of the solid-state memory.
A disk storage media may also use an indirection system to facilitate the rewriting of data associated with a particular logical address at different physical locations on the storage media. Such an indirection system may, for example, provide for sequential writing on the disk so that tracks can be written in an overlapping pattern using Shingled Magnetic Recording (SMR) to increase the amount of data stored in a given area on the disk. In such SMR DSDs, data is generally written sequentially to avoid rewriting an overlapped track on the disk since such rewriting would also adversely affect data written in an adjacent track.
Since the data capacity of storage media is generally limited, there is a need to conserve the physical space used for storing data on the storage media. This need is heightened for DSDs using an indirection system where data associated with a particular logical address is not rewritten in the same physical location on the storage media. The conservation of physical storage space typically becomes more important for such storage media since invalid or previous versions of data often remain in their old physical locations on the storage media until a maintenance operation such as garbage collection is performed to reclaim the portions of the storage media storing the invalid or obsolete data.